Facial masks are well known for use in continuous positive airway pressure (CPAP) treatment of various respiratory ailments and sleep disordered breathing (SDB), such as, for example, obstructive sleep apnea (OSA) and/or other ventilatory assistance treatments such as noninvasive positive pressure ventilation (NPPV). See, for example, U.S. Pat. No. 4,944,210, the entire content of which is expressly incorporated hereinto by reference. While the present invention will be described below with reference to a full facial mask for use in CPAP treatment, it will be understood that such a reference is non-limiting and is directed toward a particularly preferred embodiment of the present invention. Thus, the various characteristics and advantages of the present invention could equivalently be embodied in another type of mask, such as a nasal mask, or in another type of noninvasive ventilation treatment.
Apparatus for the treatment of SDB generally involves a blower which delivers a supply of air at positive pressure to a patient interface via a conduit. The patient interface may take several forms, such as a nasal mask assembly and a nasal and mouth mask assembly (i.e., a full face mask). Patients typically wear a mask assembly while sleeping to receive the NPPV therapy.
Mask assemblies typically include a rigid shell or frame and a soft face-contacting cushion. The cushion cushions the rigid frame from the patient's face, and provides a seal with the patient's face. The frame and cushion define a cavity which receives the nose or nose and mouth. The frame and cushion are held in position on the patient's face by a headgear assembly. The headgear assembly typically comprises an arrangement of straps which pass along both sides of the patient's face to the back or crown of the patient's head.
One problem that arises with existing masks used for CPAP treatments is that tightening of the mask straps results in compression of the mask against the wearer's face which may therefore apply undue force against certain of the wearer's facial features, such as the wearer's nose. A poorly fitting mask can leak when pressurized which encourages a patient to tighten the headgear straps excessively which, in turn leads to discomfort, marks on the face and in some cases facial sores.
Thus, conventional masks have been provided with a forehead support, which provides a support and stability mechanism between the mask and the forehead. The forehead support prevents both the mask from pushing too strongly against the wearer's facial region as well as minimizing movement of the mask with the addition of a contact point between the mask and the wearer's head thereby reducing uncomfortable pressure points. Furthermore, in facial masks having a gusseted facial cushion such as described in U.S. Provisional Patent Application Ser. No. 60/643,113, filed Jan. 12, 2005, the entire content of which is expressly incorporated hereinto by reference, a forehead support may be employed to control the amount of gusset opening and/or closing thereby assisting in the applied force to the wearer's face, for example, the patient's nasal region.
Typically, a mask forehead support is adjustable so that a standard mask may be capable of adjustment suitable for a number of patients with different anthropometric features. Conventional masks having adjustable forehead supports are evidenced by U.S. Pat. Nos. 6,119,693; 6,463,931; 6,557,556; and 6,691,708, the entire content of each such prior-issued patent being incorporated expressly hereinto by reference. To facilitate adjustability, conventional forehead supports may also be capable of displacement relative to the mask as shown, for example, in U.S. Pat. No. 6,532,961 (the entire content of which is expressly incorporated hereinto by reference), so as to provide a means by which the relative angle between the mask and the forehead support can be varied to accommodate the facial features of a particular wearer.
A problem with conventional forehead supports for masks, however, is that the range of adjustment is relatively limited which therefore does not in fact provide a universal fit for a relatively large number of wearers. That is, due to the anthropometric features of a particular user's head, the adjustability of conventional forehead supports may not be sufficient to allow for a comfortable fit. Thus, while the forehead supports described above perform in a satisfactory manner, improvements to forehead supports for masks are needed.